CN111157936A - Rogowski coil high-precision calibration method and equipment for measuring pulse large current source - Google Patents
Rogowski coil high-precision calibration method and equipment for measuring pulse large current source Download PDFInfo
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- CN111157936A CN111157936A CN201911058595.5A CN201911058595A CN111157936A CN 111157936 A CN111157936 A CN 111157936A CN 201911058595 A CN201911058595 A CN 201911058595A CN 111157936 A CN111157936 A CN 111157936A
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- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
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- G01R35/005—Calibrating; Standards or reference devices, e.g. voltage or resistance standards, "golden" references
- G01R35/007—Standards or reference devices, e.g. voltage or resistance standards, "golden references"
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
- G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
- G01R15/18—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers
- G01R15/181—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers using coils without a magnetic core, e.g. Rogowski coils
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Abstract
The invention discloses a high-precision calibration method of a Rogowski coil for measuring a pulse large current source, which comprises the following steps: s1, building an adjustable hundred-A-level precision current test source; s2, building a Rogowski coil scale factor calibration test system; s3, calibrating the current amplitude of the Rogowski coil scale factor; s4, calibrating the scale factor frequency of the Rogowski coil wire; s5, verifying after calibration of Rogowski coil scale factors, and also discloses equipment for realizing the Rogowski coil high-precision calibration method for measuring the pulse large current source, wherein the requirement of test equipment, test difficulty and test safety can be effectively reduced by adopting a precise small current source to replace a traditional high-power pulse current source as a calibration source; the precise calibration method combining Rogowski coil scale factor current amplitude calibration and frequency calibration is adopted, the influence of amplitude and frequency change on measurement precision in pulse measurement is effectively reduced, and the Rogowski coil calibration precision can be obviously improved compared with the traditional calibration.
Description
Technical Field
The invention relates to the technical field of pulse heavy current source measurement, in particular to a high-precision calibration method and high-precision calibration equipment for a Rogowski coil for measuring a pulse heavy current source.
Background
The high-power pulse electric energy source is a key component of electromagnetic emission equipment and has the characteristics of high voltage (more than thousands of volts), large current (more than thousands of amperes), fast pulse (micro nanosecond), high power (megawatt level) and the like. Parameters such as amplitude characteristics, phase characteristics, frequency characteristics and the like of Pulse Forming Network (PFN) current of the high-power pulse electric energy source are indexes for measuring the performance of the high-power pulse electric energy source, and the simulation verification, the optimization design and the accurate performance evaluation of a discharge loop of the whole high-power pulse electric energy source can be carried out by measuring the characteristics. How to measure the ultimate electrical performance of a high-power pulse electrical energy source is one of the problems to be solved urgently at present.
Further, for the measurement of the MW-grade PFN discharge circuit, the most common measurement means at present is to use the rogowski coil as a front-end current sensor, collect current signals by setting an integral mode and using a high-precision collection device, and obtain the current of the discharge circuit by back-solving with a scale factor given before the rogowski coil leaves the factory. Although the amplitude range and the measurement frequency of the rogowski coil meet the measurement of the PFN discharge circuit, the measurement error generated by the current solving mode based on the fixed scale factor is usually over 1 percent, the actual test requirement cannot be met, and how to reduce the measurement error of the rogowski coil is one of the key technologies for PFN discharge circuit measurement.
Furthermore, the traditional method for improving the measurement accuracy of the rogowski coil is to calibrate the calibration factor of the rogowski coil, and the calibration method usually selects a coaxial shunt to be connected in series in a PFN discharge circuit, measures the voltage at two ends of the coaxial shunt, and outputs the actual calibration factor by comparing with the rogowski coil measurement. The calibrated scale factor is more suitable for the measurement field condition, so the method can improve the Rogowski coil measurement accuracy to a certain extent, but the existing calibration means has the following defects:
(1) the accuracy of the calibration is low. The requirement of a high-power pulse power source on the measurement precision of the Rogowski coil is within 5 per thousand, and the calibration precision of the calibration method cannot meet the requirement;
(2) the scale factor is less applicable under the condition of single frequency. In actual measurement, due to the self characteristics of the rogowski coil and the comprehensive influence of the conditioning circuit, the rogowski coil has large scale factor difference under different frequency conditions, and the calibration method of the scale factor under the fixed frequency condition has a good effect on a 50Hz power frequency large current test occasion, but cannot meet the high-precision measurement requirement of a PFN discharge loop which is a measurement object with wide frequency spectrum component distribution. Therefore, how to reduce the influence of the frequency on the scale factor is another problem of solving the measurement of the PFN discharge loop.
Aiming at the problems that the MW-level power pulse electric energy for calibration is less, the installation difficulty of a measurement method adopting coaxial shunts connected in series is higher, adverse factors are easily generated on testers and test equipment, and how to improve the safety of the testers and the test equipment is one of the key points of Rogowski coil calibration.
Disclosure of Invention
Embodiments of the present invention aim to provide a method and an apparatus for calibrating a rogowski coil with high precision for pulsed high current source measurement to solve the above problems.
In order to achieve the purpose, the invention provides the following technical scheme:
a Rogowski coil high-precision calibration method for measuring a pulse large current source comprises the following steps:
s1, establishing an adjustable hundred-A-level precision current test source:
the high-power precise current generating source is formed by a signal generator and a precise power amplifier, meanwhile, a low-temperature drift precise resistor is used as a load resistor, a precise current testing source is built, an output channel of the signal generator is connected to a signal input interface of the precise power amplifier, an output terminal of the precise power amplifier is connected with a load resistor array in parallel, the type, amplitude characteristic and frequency characteristic of a signal flowing through the load current are changed by adjusting the signal type and amplitude of the signal generator and the proportional magnitude of the precise power amplifier, and the testing source is provided for the linearity calibration and frequency calibration of the Rogowski coil; a multi-turn coil is wound on a current loop and penetrates through a Rogowski coil, the maximum primary current flowing through the interior of the Rogowski coil is increased to 500A, and the Rogowski coil induces the following currents:
wherein, IGeneral assemblyIs the total primary current flowing through the Rogowski coil; n is the number of turns of the coil; v is the voltage at two ends of the load resistor; r is a load resistor;
the output amplitude can be obtained according to the factory scale factor K:
s2, establishing a Rogowski coil scale factor calibration test system:
the calibration test system comprises a tested Rogowski coil, a hundred-A-level precision current test source, a functional digital multimeter, a high-precision data acquisition card, an upper computer and an acquisition analysis software module; the functional digital multimeter probes are respectively arranged at two ends of the load resistor and used for measuring voltage and resistance at two ends of the load resistor of the current test source to obtain current flowing through the load resistor; calculating the actual current flowing through the Rogowski coil according to the number of turns of the coil; the high-precision data acquisition card, the upper computer and the acquisition and analysis software module form a Rogowski coil output voltage testing unit, and the output voltage amplitude is acquired in real time; according to a scale factor calculation formula: k is ═ Iin/VoutThe scale factor value can be calculated; wherein, IinIs primary side current, VoutOutputting voltage for the Rogowski coil;
s3, calibrating current amplitude of Rogowski coil scale factor:
setting an input waveform and an input frequency of a signal generator, changing a proportional coefficient of a power amplifier to adjust the size of a primary side input current, measuring a plurality of groups of load voltages, load resistors and output voltages of the Rogowski coil by using a calibration test system under the condition of different proportional coefficients, and averaging; wherein the average value of the load voltage is
Mean value of load resistance of
Output voltage mean value of Rogowski coil is
According to the primary side current calculation formula
The actual primary side current mean value under different magnification conditions can be obtained:
according to K ═ Iin/VoutThe mean scale factor values under different current conditions can be calculated:
to the measured
And
and performing linear fitting to obtain a relation between the scale factor and the current amplitude change:
the linearity delta of the fitted straight line is worked out, and the delta is within 3 per thousand, so that the influence of the current amplitude change on the scale factor is small, and the method for extrapolating the scale factor under the high-current condition by adopting the low-current generating source has feasibility;
s4, calibrating the Rogowski coil scale factor frequency:
the sine wave is used as signal input, the multiple of the amplifier is set to be fixed, the sine wave input frequency is changed at equal intervals, and the mean value of scale factors under different frequency conditions is measured according to a similar method in S3; at the same time, according to
And corresponding f ═ f1，f2,f3,…fn]And (3) performing curve fitting to obtain the relation between the scale factor and the current frequency change:
s5, verifying after calibration of Rogowski coil scale factors:
by randomly varying the sine wave input frequency and measuring the actual current value I flowing through the Rogowski coilTotal of iAnd the voltage value output by the Rogowski coil
Solving theoretical scale factor K by using frequency of input signal to carry in frequency fitting curvei＝F(fi) The measured current value is
And calculating the relative error γ:
after calibration, the measurement error of the Rogowski coil with the nominal 1% precision under different frequency conditions is better than 5 per mill, and then the calibration requirement is met.
In one alternative: in step S1, in order to ensure that the current and voltage flowing through the load resistor are within the rated range, the low-temperature drift precision resistor is connected in parallel by 25 60 Ω high-power aluminum shell resistors, the total resistance value is controlled to be 3 Ω, and the maximum allowable current is 15A; the aluminum shell resistor has a heat dissipation effect, and meanwhile, the parallel aluminum shell resistor is placed on a large-scale heat dissipation copper sheet, so that the overhigh temperature of the resistor is avoided.
In one alternative: in step S2, the functional digital multimeter is an eight-bit half-high precision digital multimeter; the high-precision data acquisition card is a 16-bit data acquisition card and is used for reducing the error of a measuring instrument and ensuring the accuracy of measuring the mean voltage of the sine wave and the load resistance.
In one alternative: in step S2, the upper computer measurement software has functions of waveform display, waveform spectrum analysis, amplitude measurement, and rise time measurement, and during sine wave measurement, the measured voltage peak is converted into a voltage effective value for scale factor calculation.
In one alternative: in step S3, the current amplitude variation range is 50A-500A, and the signal source input signal frequency is 100 Hz; if the function linearity delta between the measured amplitude and the scale factor is better than 3 per thousand, the scale factor of the current amplitude change under each frequency condition is averaged and used as a fixed scale factor; if the linearity is poor, the effect of the amplitude change on the scale factor is fitted to a curve and the frequency calibration curve of S4 is error corrected.
In one alternative: in step S4, according to the measurement characteristics of the Rogowski coil, the frequency variation range in the frequency calibration process is 100 Hz-10 KHz, and the equidistant interval is 50 Hz; to improve the calibration accuracy, the measured calibration data were averaged into 50 sets.
In one alternative: in steps S3 and S4, the influence of the current amplitude variation on the scale factor can be used as a fixed error correction factor to correct the frequency model, and the correction method is as follows:
(3) setting the amplitude correction factor to Kv, fixing the amplitude IfUnder the condition of a function of
Corresponding error correction function is
(4) Kv is calculated as follows:
① if
Degree of linearity δ<3‰，Kv＝1；
② if
Degree of linearity δ>3‰，
In one alternative: the specific calibration working process comprises the following steps:
①, setting up a calibration test system for Rogowski coil scale factors, and testing whether the output signal is distorted by using an oscilloscope;
② setting the frequency of the signal source and the amplification factor of the precision amplifier;
③ the test system works stably for 30min to ensure the resistance value of the load resistor to change stably;
④ measuring the load voltage with multifunctional digital multimeter for multiple times, and collecting output voltage of Rogowski coil with labview software program for multiple times;
⑤ after the single test, cutting off the power to measure the load resistance value;
⑥ facilitating all amplitude and frequency values in the same measurement step;
⑦ fitting an amplitude change curve and a frequency curve, and verifying the precision after calibration;
⑧ the calibration test is finished if the precision meets the requirement after calibration.
A rogowski coil high accuracy calibration apparatus for pulsed high current source measurements, comprising:
a memory for storing a program;
and the processor is used for realizing the steps of the Rogowski coil high-precision calibration method for the pulsed large current source measurement when executing the program stored in the memory.
A storage medium having stored thereon a computer program for execution by a processor to implement the steps of the above-described method for high precision calibration of a rogowski coil for pulsed high current source measurements.
Compared with the prior art, the embodiment of the invention has the following beneficial effects:
the requirement of test equipment, test difficulty and test safety can be effectively reduced by adopting a precise small current source to replace a traditional high-power pulse current source as a calibration source; meanwhile, a fine calibration method combining Rogowski coil scale factor current amplitude calibration and frequency calibration is adopted, the influence of amplitude and frequency change on measurement precision in pulse measurement is effectively reduced, and the Rogowski coil calibration precision can be obviously improved compared with the traditional calibration.
Drawings
FIG. 1 is a flow chart of a Rogowski coil high-precision calibration method for pulsed high current source measurement according to a first embodiment of the present invention;
fig. 2 is a structural diagram of the calibration test system for calibration factor of rogowski coil set up in step S2 in fig. 1;
FIG. 3 is a flow chart of a calibration process.
In the figure, 101-a signal generator, 102-a precision power amplifier, 103-a load resistor, 201-a Rogowski coil to be tested, 202-a functional digital multimeter, 203-a high-precision data acquisition card, 204-an upper computer and 205-an acquisition and analysis software module
Detailed Description
The present invention will be described in detail with reference to the following embodiments, which are illustrated in the accompanying drawings or description, wherein like or similar elements are designated by the same reference numerals. The examples are given solely for the purpose of illustration and are not intended to limit the scope of the invention. Any obvious modifications or variations can be made to the present invention without departing from the spirit or scope of the present invention.
Example 1
Referring to fig. 1 to 3, in an embodiment of the present invention, a method for calibrating a rogowski coil in high precision for measuring a pulsed large current source includes the following steps:
s1, establishing an adjustable hundred-A-level precision current test source:
the high-power precise current generating source is formed by a signal generator and a precise power amplifier, meanwhile, a low-temperature drift precise resistor is used as a load resistor, a precise current testing source is built, an output channel of the signal generator is connected to a signal input interface of the precise power amplifier, an output terminal of the precise power amplifier is connected with a load resistor array in parallel, the type, amplitude characteristic and frequency characteristic of a signal flowing through the load current are changed by adjusting the signal type and amplitude of the signal generator and the proportional magnitude of the precise power amplifier, and the testing source is provided for the linearity calibration and frequency calibration of the Rogowski coil; the multiturn coil 104 is wound on the current loop and passes through the rogowski coil, the maximum primary current flowing through the interior of the rogowski coil is increased to 500A, and the current induced by the rogowski coil is as follows:
wherein, IGeneral assemblyIs the total primary current flowing through the Rogowski coil; n is the number of turns of the coil; v is the voltage at two ends of the load resistor; r is a load resistor;
the output amplitude can be obtained according to the factory scale factor K:
s2, establishing a Rogowski coil scale factor calibration test system:
the calibration test system comprises a tested Rogowski coil, a hundred-A-level precision current test source, a functional digital multimeter, a high-precision data acquisition card, an upper computer and an acquisition analysis software module; the functional digital multimeter probes are respectively arranged at two ends of the load resistor and used for measuring voltage and resistance at two ends of the load resistor of the current test source to obtain current flowing through the load resistor; calculating the actual current flowing through the Rogowski coil according to the number of turns of the coil; the high-precision data acquisition card, the upper computer and the acquisition and analysis software module form a Rogowski coil output voltage testing unit, and the output voltage amplitude is acquired in real time; according to a scale factor calculation formula: k is ═ Iin/VoutA scale factor value can be calculated, wherein IinIs primary side current, VoutOutputting voltage for the Rogowski coil;
s3, calibrating current amplitude of Rogowski coil scale factor:
set signal generator outputThe input waveform and the input frequency are changed, the proportional coefficient of the power amplifier is changed to adjust the primary side input current, and a calibration test system is used for measuring a plurality of groups of load voltages, load resistors and output voltages of the Rogowski coil under different proportional coefficient conditions and calculating the average value; wherein the average value of the load voltage is
Mean value of load resistance of
Output voltage mean value of Rogowski coil is
According to the primary side current calculation formula
The actual primary side current mean value under different magnification conditions can be obtained:
according to K ═ Iin/VoutThe mean scale factor values under different current conditions can be calculated:
to the measured
And
and performing linear fitting to obtain a relation between the scale factor and the current amplitude change:
and solving the linearity delta of the fitted straight line, wherein the delta is within 3 per thousand, which indicates that the influence of the current amplitude change on the scale factor is small, and the scale factor under the condition of large current is extrapolated by adopting a small current generating sourceThe method has feasibility;
s4, calibrating the Rogowski coil scale factor frequency:
the sine wave is used as signal input, the multiple of the amplifier is set to be fixed, the sine wave input frequency is changed at equal intervals, and the mean value of scale factors under different frequency conditions is measured according to a similar method in S3; at the same time, according to
And corresponding f ═ f1，f2,f3,…fn]And (3) performing curve fitting to obtain the relation between the scale factor and the current frequency change:
s5, verifying after calibration of Rogowski coil scale factors:
by randomly varying the sine wave input frequency and measuring the actual current value I flowing through the Rogowski coilTotal of iAnd the voltage value output by the Rogowski coil
Solving theoretical scale factor K by using frequency of input signal to carry in frequency fitting curvei＝F(fi) The measured current value is
And calculating the relative error γ:
after calibration, the measurement error of the Rogowski coil with the nominal 1% precision under different frequency conditions is better than 5 per mill, and then the calibration requirement is met.
In step S1, in order to ensure that the current and voltage flowing through the load resistor are within the rated range, the low-temperature-drift precision resistor is connected in parallel by 25 60 Ω high-power aluminum shell resistors, the total resistance value is controlled to be 3 Ω, and the maximum allowable current is 15A; the aluminum shell resistor has a heat dissipation effect, and meanwhile, the parallel aluminum shell resistor is placed on a large-scale heat dissipation copper sheet, so that the overhigh temperature of the resistor is avoided.
In step S2, the functional digital multimeter is an eight-bit half-high precision digital multimeter; the high-precision data acquisition card is a 16-bit data acquisition card and is used for reducing the error of a measuring instrument and ensuring the accuracy of measuring the mean voltage of the sine wave and the load resistance.
In step S2, the upper computer measurement software has functions of waveform display, waveform spectrum analysis, amplitude measurement, and rise time measurement, and during sine wave measurement, the measured voltage peak is converted into a voltage effective value for scale factor calculation.
In step S3, the current amplitude variation range is 50A-500A, and the signal source input signal frequency is 100 Hz; if the function linearity delta between the measured amplitude and the scale factor is better than 3 per thousand, the scale factor of the current amplitude change under each frequency condition is averaged and used as a fixed scale factor; if the linearity is poor, the effect of the amplitude change on the scale factor is fitted to a curve and the frequency calibration curve of S4 is error corrected.
In step S4, according to the measurement characteristics of the Rogowski coil, the frequency variation range in the frequency calibration process is 100 Hz-10 KHz, and the equidistant interval is 50 Hz; to improve the calibration accuracy, the measured calibration data were averaged into 50 sets.
In steps S3 and S4, the influence of the current amplitude variation on the scale factor can be used as a fixed error correction factor to correct the frequency model, and the correction method is as follows:
(5) setting the amplitude correction factor to Kv, fixing the amplitude IfUnder the condition of a function of
Corresponding error correction function is
(6) Kv is calculated as follows:
① if
Degree of linearity δ<3‰，Kv＝1；
② if
Degree of linearity δ>3‰，
The specific calibration working process comprises the following steps:
①, setting up a calibration test system for Rogowski coil scale factors, and testing whether the output signal is distorted by using an oscilloscope;
② setting the frequency of the signal source and the amplification factor of the precision amplifier;
③ the test system works stably for 30min to ensure the resistance value of the load resistor to change stably;
④ measuring the load voltage with multifunctional digital multimeter for multiple times, and collecting output voltage of Rogowski coil with labview software program for multiple times;
⑤ after the single test, cutting off the power to measure the load resistance value;
⑥ facilitating all amplitude and frequency values in the same measurement step;
⑦ fitting an amplitude change curve and a frequency curve, and verifying the precision after calibration;
⑧ the calibration test is finished if the precision meets the requirement after calibration.
Example 2
A rogowski coil high accuracy calibration apparatus for pulsed high current source measurements, comprising:
a memory for storing a program;
and the processor is used for implementing the steps of the Rogowski coil high-precision calibration method for the pulse large current source measurement in the embodiment 1 when executing the program stored in the memory.
Example 3
A storage medium having stored thereon a computer program for execution by a processor to perform the steps of the method for high precision calibration of a rogowski coil for pulsed high current source measurement of the embodiments.
The above description is only for the specific embodiments of the present disclosure, but the scope of the present disclosure is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present disclosure, and all the changes or substitutions should be covered within the scope of the present disclosure. Therefore, the protection scope of the present disclosure shall be subject to the protection scope of the claims.
Claims (9)
1. A Rogowski coil high-precision calibration method for measuring a pulse large current source is characterized by comprising the following steps:
s1, establishing an adjustable hundred-A-level precision current test source:
the high-power precise current generating source is formed by a signal generator and a precise power amplifier, meanwhile, a low-temperature drift precise resistor is used as a load resistor, a precise current testing source is built, an output channel of the signal generator is connected to a signal input interface of the precise power amplifier, an output terminal of the precise power amplifier is connected with a load resistor array in parallel, the type, amplitude characteristic and frequency characteristic of a signal flowing through the load current are changed by adjusting the signal type and amplitude of the signal generator and the proportional magnitude of the precise power amplifier, and the testing source is provided for the linearity calibration and frequency calibration of the Rogowski coil; a multi-turn coil is wound on a current loop and penetrates through a Rogowski coil, the maximum primary current flowing through the interior of the Rogowski coil is increased to 500A, and the Rogowski coil induces the following currents:
wherein, IGeneral assemblyIs the total primary current flowing through the Rogowski coil; n is the number of turns of the coil; v is the voltage at two ends of the load resistor; r is a load resistor;
the output amplitude can be obtained according to the factory scale factor K:
s2, establishing a Rogowski coil scale factor calibration test system:
the calibration test system comprises a tested Rogowski coil, a hundred-A-level precision current test source, a functional digital multimeter, a high-precision data acquisition card, an upper computer and an acquisition analysis software module; the functional digital multimeter probes are respectively arranged at two ends of the load resistor and used for measuring voltage and resistance at two ends of the load resistor of the current test source to obtain current flowing through the load resistor; calculating the actual current flowing through the Rogowski coil according to the number of turns of the coil; the high-precision data acquisition card, the upper computer and the acquisition and analysis software module form a Rogowski coil output voltage testing unit, and the output voltage amplitude is acquired in real time; according to a scale factor calculation formula: k is ═ Iin/VoutThe scale factor value can be calculated; wherein, IinIs primary side current, VoutOutputting voltage for the Rogowski coil;
s3, calibrating current amplitude of Rogowski coil scale factor:
setting an input waveform and an input frequency of a signal generator, changing a proportional coefficient of a power amplifier to adjust the size of a primary side input current, measuring a plurality of groups of load voltages, load resistors and output voltages of the Rogowski coil by using a calibration test system under the condition of different proportional coefficients, and averaging; wherein the average value of the load voltage is
Mean value of load resistance of
Output voltage mean value of Rogowski coil is
According to the primary side current calculation formula
The actual primary side current mean value under different magnification conditions can be obtained:
according to K ═ Iin/VoutThe mean scale factor values under different current conditions can be calculated:
to the measured
And
and performing linear fitting to obtain a relation between the scale factor and the current amplitude change:
the linearity delta of the fitted straight line is worked out, and the delta is within 3 per thousand, so that the influence of the current amplitude change on the scale factor is small, and the method for extrapolating the scale factor under the high-current condition by adopting the low-current generating source has feasibility;
s4, calibrating the Rogowski coil scale factor frequency:
the sine wave is used as signal input, the multiple of the amplifier is set to be fixed, the sine wave input frequency is changed at equal intervals, and the mean value of scale factors under different frequency conditions is measured according to a similar method in S3; at the same time, according to
And corresponding f ═ f1，f2,f3,…fn]And (3) performing curve fitting to obtain the relation between the scale factor and the current frequency change:
s5, verifying after calibration of Rogowski coil scale factors:
by randomly varying the sine wave input frequency and measuring the actual current value I flowing through the Rogowski coilTotal of iAnd the voltage value output by the Rogowski coil
Solving theoretical scale factor K by using frequency of input signal to carry in frequency fitting curvei＝F(fi) The measured current value is
And calculating the relative error γ:
after calibration, the measurement error of the Rogowski coil with the nominal 1% precision under different frequency conditions is better than 5 per mill, and then the calibration requirement is met.
2. The Rogowski coil high-precision calibration method for pulsed large current source measurement as claimed in claim 1, wherein in step S1, in order to ensure that the current and voltage flowing through the load resistor are within the rated range, the low temperature drift precision resistor is connected in parallel by 25 60 Ω high-power aluminum shell resistors, the total resistance value is controlled to be 3 Ω, and the maximum allowed current is 15A; the aluminum shell resistor has a heat dissipation effect, and meanwhile, the parallel aluminum shell resistor is placed on a large-scale heat dissipation copper sheet, so that the overhigh temperature of the resistor is avoided.
3. The Rogowski coil high-precision calibration method for pulsed high current source measurement according to claim 1, wherein in step S2, the functional digital multimeter is an eight-bit and half-high-precision digital multimeter; the high-precision data acquisition card is a 16-bit data acquisition card and is used for reducing the error of a measuring instrument and ensuring the accuracy of measuring the mean voltage of the sine wave and the load resistance.
4. The method for calibrating the rogowski coil high accuracy for pulsed high current source measurement according to claim 1, wherein in step S2, the upper computer measurement software has functions of waveform display, waveform spectrum analysis, amplitude measurement and rise time measurement, and during sine wave measurement, the measured voltage peak is converted into a voltage effective value for scale factor calculation.
5. The high-precision calibration method for the rogowski coil used for pulsed high current source measurement according to claim 1, wherein in step S3, the current amplitude variation range is 50A-500A, and the signal source input signal frequency is 100 Hz; if the function linearity delta between the measured amplitude and the scale factor is better than 3 per thousand, the scale factor of the current amplitude change under each frequency condition is averaged and used as a fixed scale factor; if the linearity is poor, the effect of the amplitude change on the scale factor is fitted to a curve and the frequency calibration curve of S4 is error corrected.
6. The method for calibrating the rogowski coil high accuracy for pulsed high current source measurement according to claim 1, wherein in step S4, according to the measurement characteristics of the rogowski coil, the frequency variation range in the frequency calibration process is 100Hz to 10KHz, and the equidistant interval is 50 Hz; to improve the calibration accuracy, the measured calibration data were averaged into 50 sets.
7. The Rogowski coil high accuracy calibration method for pulsed high current source measurement as claimed in claim 1, wherein in steps S3 and S4, the influence of the current amplitude variation on the scale factor can be used as a fixed error correction factor to correct the frequency model, the correction method is as follows:
(1) setting the amplitude correction factor to Kv, fixing the amplitude IfUnder the condition of a function of
Corresponding error correction function is
(2) Kv is calculated as follows:
① if
Degree of linearity δ<3‰，Kv＝1；
② if
Degree of linearity δ>3‰，
8. The high-precision calibration method for the Rogowski coil used for the pulsed high current source measurement according to any one of claims 1-7, characterized in that the specific calibration working process is as follows:
①, setting up a calibration test system for Rogowski coil scale factors, and testing whether the output signal is distorted by using an oscilloscope;
② setting the frequency of the signal source and the amplification factor of the precision amplifier;
③ the test system works stably for 30min to ensure the resistance value of the load resistor to change stably;
④ measuring the load voltage with multifunctional digital multimeter for multiple times, and collecting output voltage of Rogowski coil with labview software program for multiple times;
⑤ after the single test, cutting off the power to measure the load resistance value;
⑥ facilitating all amplitude and frequency values in the same measurement step;
⑦ fitting an amplitude change curve and a frequency curve, and verifying the precision after calibration;
⑧ the calibration test is finished if the precision meets the requirement after calibration.
9. A Rogowski coil high-precision calibration device for pulsed high current source measurement, comprising:
a memory for storing a program;
a processor for implementing the steps of the rogowski coil high accuracy calibration method for pulsed high current source measurement as claimed in any one of claims 1-7 when executing a program stored in a memory.
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| CN201911058595.5A CN111157936A (en) | 2019-11-01 | 2019-11-01 | Rogowski coil high-precision calibration method and equipment for measuring pulse large current source |
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